BTW, I know that could be just treat as vendor stuff for upstream, but this touch lots stuff including introducing new mechanism and new ELF section, so I really hope this is not just a vendor extension, also many RISC-V vendor might also benefit this since one selling point of RISC-V is customize-able :)
Kito Cheng <[email protected]> 於 2026年5月25日週一 下午10:28寫道： > > Let me repeat my reply on binutils list here :) > > Hi Luis: > > I like this approach in general, but I would like to discuss that on > toolchain sig meeting to make sure we can reaching a consensus for > that between LLVM and GNU community, also make it standardize before > we moving forward. > > Are you interested in presenting that and creating a PR to > https://github.com/riscv-non-isa/riscv-c-api-doc to start the > discussion? also it would be nice if you can present that on toolchain > sig meeting :) > > Luis Silva <[email protected]> 於 2026年5月25日週一 下午10:26寫道： > > > > This series adds support for the RISC-V APEX (ARC Processor EXtension) > > custom instruction mechanism to GCC. APEX allows users to declare > > custom instructions at the C source level using #pragma intrinsic and > > have the compiler generate the appropriate assembly, including > > .extInstruction directives for the assembler. > > > > This work was presented at the GNU Cauldron 2025. > > - https://www.youtube.com/watch?v=jHfxkAN3Qtw > > > > Jeff Law also attended the presentation and is CC'd on this series. > > > > APEX is not a new ISA extension in the traditional sense -- it does not > > add new -march bits or predefined builtins. Instead, it provides a > > pragma-driven interface where users bind C function declarations to > > custom instruction opcodes at compile time. The compiler then replaces > > calls to those functions with custom instructions. > > > > source file: > > int foo_func (int, int); > > #pragma intrinsic (foo_func, "foo", 7, XD) > > int > > main (void) > > { > > return foo_func (1, 2); > > } > > > > output: > > main: > > li a5,2 > > li a0,1 > > foo a0,a0,a5 # APEX insn. > > ret > > > > Four instruction formats are supported: > > - XD: register-register (up to 3 operands, 8-bit opcode) > > - XS: short-immediate (two registers + 8-bit signed immediate, 6-bit > > opcode) > > - XI: immediate (one register + immediate, 5-bit opcode) > > - XC: accumulator (dest = src0, 5-bit opcode) > > > > When no format is explicitly specified, the compiler infers it from the > > function signature and opcode range. Multiple formats can be specified > > for a single intrinsic (except XI, which is exclusive); the compiler > > selects the appropriate encoding at each call site. > > > > Since APEX intrinsics are registered dynamically via pragmas, their > > metadata must be explicitly serialized to survive link-time optimization. > > The implementation adds a dedicated LTO section (LTO_section_riscv_apex) > > with read/write hooks guarded by TARGET_RISCV_APEX. I initially > > considered a generic target hook for LTO section read/write, but since > > this is currently RISC-V specific, that would impose interface > > requirements on other architectures that do not need it. If other > > targets develop similar needs in the future, a common hook can be > > factored out at that point. > > > > The directive syntax and instruction formats in this RISCV-V APEX port > > are intentionally aligned with existing proprietary compiler and > > architecture to maintain compatibility across toolchains. > > > > The binutils-gdb patch series adding APEX assembler and disassembler > > support has been submitted for review: > > https://sourceware.org/pipermail/binutils/2026-May/149426.html > > > > The "[4/4] RISC-V: Add APEX LTO serialization for intrinsics" patch > > depends on: > > 1. The binutils APEX support above (for testing) > > 2. The previously submitted patch: > > "testsuite: Add dg-lto-error directive and ltrans assembly scanning" > > https://gcc.gnu.org/pipermail/gcc-patches/2026-May/716427.html > > which adds generic LTO test infrastructure used by the APEX LTO tests. > > > > The series is structured as follows: > > > > [1/4] RISC-V: Add APEX backend machine description and constraints > > RTL patterns (define_insn/define_expand) for all APEX instruction > > formats, mode iterators, constraints, and the .extInstruction > > emission helper. > > > > [2/4] RISC-V: Add APEX middle-end builtin registration and expansion > > Dynamic builtin table, format inference, opcode validation, > > immediate range checks, and RTL expansion. > > > > [3/4] RISC-V: Add APEX #pragma intrinsic frontend > > C pragma parser, mnemonic validation, function lookup, format > > flag parsing, and user-facing documentation in extend.texi. > > > > [4/4] RISC-V: Add APEX LTO serialization for intrinsics > > Custom LTO section serialization/deserialization with > > cross-translation-unit conflict detection, plus LTO tests. > > > > Tested on riscv64-unknown-elf and riscv32-unknown-elf with no > > regressions. > > > > Luis Silva (4): > > RISC-V: Add APEX backend machine description and constraints > > RISC-V: Add APEX middle-end builtin registration and expansion > > RISC-V: Add APEX #pragma intrinsic frontend > > RISC-V: Add APEX LTO serialization for intrinsics > > > > gcc/config.gcc | 1 + > > gcc/config/riscv/arcv-apex.md | 367 +++++++++ > > gcc/config/riscv/arcv-builtins.cc | 760 ++++++++++++++++++ > > gcc/config/riscv/arcv.cc | 102 +++ > > gcc/config/riscv/constraints.md | 34 + > > gcc/config/riscv/iterators.md | 6 + > > gcc/config/riscv/riscv-builtins.cc | 14 + > > gcc/config/riscv/riscv-c.cc | 224 ++++++ > > gcc/config/riscv/riscv-protos.h | 20 +- > > gcc/config/riscv/riscv-vector-builtins.h | 8 +- > > gcc/config/riscv/riscv.h | 42 + > > gcc/config/riscv/riscv.md | 1 + > > gcc/config/riscv/t-riscv | 16 + > > gcc/doc/extend.texi | 85 ++ > > gcc/fold-const.cc | 12 + > > gcc/lto-section-in.cc | 1 + > > gcc/lto-streamer-out.cc | 6 + > > gcc/lto-streamer.h | 6 + > > gcc/lto/lto-common.cc | 6 + > > gcc/testsuite/g++.target/riscv/apex/apex.exp | 30 + > > .../g++.target/riscv/apex/arcv-apex-test1.C | 22 + > > .../g++.target/riscv/apex/arcv-apex-test2.C | 14 + > > .../g++.target/riscv/apex/arcv-apex-test3.C | 21 + > > .../g++.target/riscv/apex/arcv-apex-test4.C | 33 + > > .../g++.target/riscv/apex/arcv-apex-test5.C | 16 + > > gcc/testsuite/gcc.target/riscv/apex/apex.exp | 53 ++ > > .../gcc.target/riscv/apex/arcv-apex-err1.c | 4 + > > .../gcc.target/riscv/apex/arcv-apex-err10.c | 14 + > > .../gcc.target/riscv/apex/arcv-apex-err11.c | 11 + > > .../gcc.target/riscv/apex/arcv-apex-err12.c | 11 + > > .../gcc.target/riscv/apex/arcv-apex-err13.c | 13 + > > .../gcc.target/riscv/apex/arcv-apex-err14.c | 4 + > > .../gcc.target/riscv/apex/arcv-apex-err15.c | 9 + > > .../riscv/apex/arcv-apex-err16-32.c | 14 + > > .../riscv/apex/arcv-apex-err16-64.c | 14 + > > .../riscv/apex/arcv-apex-err17-32.c | 13 + > > .../riscv/apex/arcv-apex-err17-64.c | 13 + > > .../gcc.target/riscv/apex/arcv-apex-err18.c | 7 + > > .../gcc.target/riscv/apex/arcv-apex-err19.c | 13 + > > .../gcc.target/riscv/apex/arcv-apex-err2.c | 4 + > > .../gcc.target/riscv/apex/arcv-apex-err20.c | 16 + > > .../gcc.target/riscv/apex/arcv-apex-err3.c | 4 + > > .../gcc.target/riscv/apex/arcv-apex-err4.c | 4 + > > .../gcc.target/riscv/apex/arcv-apex-err5.c | 6 + > > .../gcc.target/riscv/apex/arcv-apex-err6.c | 4 + > > .../gcc.target/riscv/apex/arcv-apex-err7.c | 4 + > > .../gcc.target/riscv/apex/arcv-apex-err8.c | 4 + > > .../gcc.target/riscv/apex/arcv-apex-err9.c | 12 + > > .../riscv/apex/arcv-apex-lto-err1_0.c | 16 + > > .../riscv/apex/arcv-apex-lto-err1_1.c | 9 + > > .../riscv/apex/arcv-apex-lto-err2_0.c | 17 + > > .../riscv/apex/arcv-apex-lto-err2_1.c | 9 + > > .../riscv/apex/arcv-apex-lto-err3_0.c | 17 + > > .../riscv/apex/arcv-apex-lto-err3_1.c | 9 + > > .../riscv/apex/arcv-apex-lto-err4_0.c | 19 + > > .../riscv/apex/arcv-apex-lto-err4_1.c | 9 + > > .../riscv/apex/arcv-apex-lto-test1_0.c | 49 ++ > > .../riscv/apex/arcv-apex-lto-test1_1.c | 25 + > > .../riscv/apex/arcv-apex-lto-test2_0.c | 36 + > > .../riscv/apex/arcv-apex-lto-test2_1.c | 15 + > > .../riscv/apex/arcv-apex-lto-test3_0.c | 49 ++ > > .../riscv/apex/arcv-apex-lto-test3_1.c | 25 + > > .../riscv/apex/arcv-apex-lto-test4_0.c | 25 + > > .../riscv/apex/arcv-apex-lto-test4_1.c | 12 + > > .../riscv/apex/arcv-apex-lto-test5_0.c | 52 ++ > > .../riscv/apex/arcv-apex-lto-test5_1.c | 20 + > > .../gcc.target/riscv/apex/arcv-apex-test1.c | 22 + > > .../gcc.target/riscv/apex/arcv-apex-test10.c | 22 + > > .../gcc.target/riscv/apex/arcv-apex-test11.c | 22 + > > .../gcc.target/riscv/apex/arcv-apex-test12.c | 21 + > > .../gcc.target/riscv/apex/arcv-apex-test13.c | 22 + > > .../gcc.target/riscv/apex/arcv-apex-test14.c | 20 + > > .../gcc.target/riscv/apex/arcv-apex-test15.c | 20 + > > .../gcc.target/riscv/apex/arcv-apex-test16.c | 20 + > > .../gcc.target/riscv/apex/arcv-apex-test2.c | 16 + > > .../gcc.target/riscv/apex/arcv-apex-test3.c | 15 + > > .../gcc.target/riscv/apex/arcv-apex-test4.c | 39 + > > .../gcc.target/riscv/apex/arcv-apex-test5.c | 63 ++ > > .../gcc.target/riscv/apex/arcv-apex-test6.c | 63 ++ > > .../gcc.target/riscv/apex/arcv-apex-test7.c | 17 + > > .../gcc.target/riscv/apex/arcv-apex-test8.c | 17 + > > .../gcc.target/riscv/apex/arcv-apex-test9.c | 20 + > > 82 files changed, 2923 insertions(+), 7 deletions(-) > > create mode 100644 gcc/config/riscv/arcv-apex.md > > create mode 100644 gcc/config/riscv/arcv-builtins.cc > > create mode 100644 gcc/config/riscv/arcv.cc > > create mode 100644 gcc/testsuite/g++.target/riscv/apex/apex.exp > > create mode 100644 gcc/testsuite/g++.target/riscv/apex/arcv-apex-test1.C > > create mode 100644 gcc/testsuite/g++.target/riscv/apex/arcv-apex-test2.C > > create mode 100644 gcc/testsuite/g++.target/riscv/apex/arcv-apex-test3.C > > create mode 100644 gcc/testsuite/g++.target/riscv/apex/arcv-apex-test4.C > > create mode 100644 gcc/testsuite/g++.target/riscv/apex/arcv-apex-test5.C > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/apex.exp > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err1.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err10.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err11.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err12.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err13.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err14.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err15.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err16-32.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err16-64.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err17-32.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err17-64.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err18.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err19.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err2.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err20.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err3.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err4.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err5.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err6.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err7.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err8.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-err9.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-err1_0.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-err1_1.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-err2_0.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-err2_1.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-err3_0.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-err3_1.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-err4_0.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-err4_1.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-test1_0.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-test1_1.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-test2_0.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-test2_1.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-test3_0.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-test3_1.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-test4_0.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-test4_1.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-test5_0.c > > create mode 100644 > > gcc/testsuite/gcc.target/riscv/apex/arcv-apex-lto-test5_1.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test1.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test10.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test11.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test12.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test13.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test14.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test15.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test16.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test2.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test3.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test4.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test5.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test6.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test7.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test8.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/apex/arcv-apex-test9.c > > > > -- > > 2.34.0 > >
